The disclosure of Japanese Patent Application No. 2001-333065 filed on Oct. 30, 2001 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
1. Field of Invention
The invention relates to an antenna structure, and more particularly to an antenna structure for a vehicle which is suitable when a vehicle component member such as a roof panel and the like is made of an insulating material.
2. Description of Related Art
A roof portion of a vehicle, for example, is generally made of a metallic material, such as a steel sheet and the like. However, in recent years, for the purpose of weight reduction, and improvement of design, assembly workability and the like, of the vehicle, a proposal that the roof portion be made of a resin material and the like having a predetermined strength has been suggested.
For example Japanese Utility Laid-Open Publication No. 2-123108, discloses a cloth including metal fibers which has a radio wave reflecting or absorbing effect is provided as an interior trim inside the passenger compartment such that the gain of the antenna provided on the roof side is increased.
However, if the resin roof is adopted, there arises a problem that an electrical noise generated by an electrical component, such as an ECU (electronic control unit) and the like, provided in the vehicle tends to leak outside.
As mentioned above, a metallic roof panel is generally used in the vehicle, and this metallic roof has a noise insulating effect. The metallic roof panel is structured so as to suppress the electrical noise generated in the vehicle from being emitted outside.
However, using the resin roof reduces the aforementioned noise insulating effect that was achieved by the vehicle body structure itself, thereby causing a problem that the noise leaks outside.
Although, a number of proposals have been made with respect to obtaining an antenna structure with favorable characteristics in relation to making the roof portion of resin, no proposals have been made with respect to the antenna structure for the vehicle which takes into account the problem of noise leak caused by making the roof portion of resin.
It is an object of the invention to provide an antenna structure for a vehicle which takes into account the suppression of noise leak caused when a vehicle component member is made of an insulating material such as resin and the like.
It is another object of the invention to provide an antenna structure for a vehicle which also takes into account the suppression of leak of a noise generated in the vehicle.
In order to achieve the aforementioned objects, an antenna structure for a vehicle, according to a first exemplary embodiment of the invention, includes a vehicle body component member of which at least a part is made of an insulating material, a conductive film provided inside or on a surface of the insulating material, and a slot which is formed on a part of the conductive film to constitute an antenna.
According to the first exemplary embodiment of the invention, a portion of the conductive film on which the slot is formed serves as a so-called slot antenna. In addition, the conductive film functions the same as the conventional metallic roof panel, thereby blocking off the noise effectively. Accordingly, an antenna structure capable of receiving a desired radio wave while suppressing noise leak outside the vehicle can be provided. Furthermore, since the conductive film serves as the slot antenna and a noise insulating member, the number of component parts can be reduced making it possible to provide the antenna structure at low cost.
In an exemplary embodiment of the invention, a roof portion in the upper part of the vehicle is provided as a suitable example of the vehicle body component member. However, the antenna structure according to the invention can also be applied to various component members constituting a vehicle outer face, such as a luggage compartment, a fender, a door and the like, any of which is made of resin.
Further, an antenna structure for a vehicle according to a second exemplary embodiment of the invention includes a vehicle body component member of which at least a part is made of an insulating material, a conductive film provided at a certain distance from the insulating material, and a slot which is formed on a part of the conductive film to constitute an antenna.
The conductive film need not necessarily be provided in contact with the insulating material, and may be provided at a certain distance from the insulating material as in the second exemplary embodiment of the invention.
Also, according to the second exemplary embodiment of the invention, a portion of the conductive film on which the slot is formed serves as the slot antenna. In addition, the conductive film functions as the conventional metallic roof panel, thereby blocking off the noise. Accordingly, a desired radio wave can be received while suppressing noise leak outside the vehicle.
Further, in the first and second exemplary embodiments of the invention, the conductive film may be structured to be grounded on a conductive portion of the vehicle body.
According to this structure, since the conductive film is grounded on the vehicle body, the same insulation effect as that obtained with the conventional metallic roof panel can be expected.
In addition, in the second exemplary embodiment described above, the conductive film may be structured to be integrally formed with an interior trim member inside the passenger compartment.
Where the conductive film is provided at a certain distance from the insulating material, the conductive film is integrated with the interior trim member provided inside the passenger compartment, and therefore there is no need to provide a new member which is required when arranging the conductive film. Therefore, the same assembly workability as that with the conventional structure can be assured, and a preferable antenna structure can be provided in the vehicle without increasing the number of component parts.